In-situ upgrading of biomass pyrolysis vapor using acid catalyst and alcohol

ABSTRACT

Processes for thermal conversion of biomass are provided. The processes involve upgrading the pyrolysis vapor from a pyrolysis reactor. The steps include thermally converting a biomass feedstock in a pyrolysis reactor, recovering a pyrolysis vapor from the reactor, passing the pyrolysis vapor in contact with an acid catalyst in the presence of alcohol, and converting the resulting upgraded pyrolysis vapor into a liquid product. The resulting biooil liquid product is more refined, and the overall processes offer economic and energy efficiency.

TECHNICAL FIELD

The present application relates to a process of upgrading biomass pyrolysis vapor. More specifically, the present application relates to a process of in-situ upgrading of biomass pyrolysis vapor using a multi-layer catalyst bed or a cascade of catalytic reactors.

BACKGROUND

With the diminishing supply of fossil fuels, the use of renewable energy sources is becoming increasingly important as a feedstock for production of hydrocarbon compounds. Thermal conversion of carbonaceous materials, such as biomass and waste, can play an important role to provide materials that can replace fossil fuels. These conversions can be accomplished by pyrolysis processes.

Pyrolysis is one of two major pathways for converting biomass into fuels or chemicals in a thermochemical platform. The major product from a common fast pyrolysis process is called biocrude or biooil, a dark brown liquid that generally is acidic and has high oxygen and water content, which are characteristics that are usually not favored by existing refinery equipment or processes used for further processing to transportation fuels. For instance, the oxygen content could be 50 weight percent (wt %) or higher in biooil, thus requiring a high amount of hydrogen to upgrade the biooil into hydrocarbon fuels via hydroprocessing, which makes the process economically unattractive. In addition, the acidity of biooil causes the biooil to be corrosive to existing pipelines. Moreover, the water content is typically 20 to 30 wt % and the biooil is immiscible with petroleum crude, which makes co-refining difficult. Therefore, biooils with improved properties, such as with less oxygen, less water, and close to neutral pH, would be preferred.

Currently, most research on improving the properties of biooil has been focused on post-pyrolysis treatment involving upgrading the liquid biooil obtained from fast pyrolysis with hydroprocessing or hydrotreating, and other reactions like esterification. However, little or no effort has been put into in situ catalytic upgrading of pyrolysis vapor before it is condensed into liquid. For example, one common biooil upgrading method is to first separate it into two phases (aqueous and lignin phase), and then use the pyrolytic lignin phase (or organic phase) for hydroprocessing, while the aqueous phase is passed onto steam-reforming to generate the hydrogen required by the hydroprocessing. Although this approach may work, one distinct disadvantage is that both the aqueous and lignin phases have to be reheated up to high temperatures for steam reforming and hydroprocessing, which would require extra heat or energy, thus considerably reducing the overall thermal efficiency of the process.

Biomass-derived pyrolysis oil has the potential to replace up to 60 percent (%) of transportation fuels, thereby reducing the dependency on conventional petroleum and reducing its environmental impact. Therefore, there is a need in the industry for a process that is more economical and energy efficient for converting biomass to fuels.

SUMMARY

The present invention provides a process for in-situ upgrading of biomass pyrolysis vapor using a multi-layered catalyst bed or cascaded catalytic reactors. In one aspect, the present process for the thermal conversion of biomass comprises the steps of a) thermal conversion of a biomass feedstock in a pyrolysis reactor, b) recovering a pyrolysis vapor from the reactor, c) passing the pyrolysis vapor in contact with a cracking catalyst, a water-gas shift reaction catalyst, a hydrotreating catalyst, and an acid catalyst, and d) converting the resulting pyrolysis vapor from step c) into a liquid product.

In one other aspect, the present process for the thermal conversion of biomass comprises the steps of a) thermal conversion of a biomass feedstock in a pyrolysis reactor, b) recovering a pyrolysis vapor from the reactor, c) passing the pyrolysis vapor in contact with an acid catalyst in the presence of an alcohol, and d) converting the resulting pyrolysis vapor from step c) into a liquid product.

In another aspect, the present process for the thermal conversion of biomass comprises the steps of a) thermal conversion of a biomass feedstock in a pyrolysis reactor, b) recovering a pyrolysis vapor from the reactor, c) passing the pyrolysis vapor in contact with a water-gas shift reaction catalyst and a hydrotreating catalyst, and d) converting the resulting pyrolysis vapor from step c) into a liquid product.

In yet another aspect, the present process for the thermal conversion of biomass comprises the steps of a) thermal conversion of a biomass feedstock in a pyrolysis reactor, b) recovering a pyrolysis vapor from the reactor, c) passing the pyrolysis vapor in contact with a cracking catalyst, a water-gas shift reaction catalyst, and a hydrotreating catalyst, and d) converting the resulting pyrolysis vapor from step c) into a liquid product.

Among other factors, it has been found that by in-situ upgrading the biomass pyrolysis vapor using the series of catalysts of the present processes, a liquid biooil product is obtained that is so refined that the liquid product can be combined with crude oil to make gasoline. In addition, it has been found that by in-situ upgrading the biomass pyrolysis vapor to have less acidity, one can attain a liquid biooil product which is easier to handle and less corrosive in post-pyrolysis treatment. It has also been found that in-situ upgrading of hot pyrolysis vapor is more attractive and economical, as biooil with improved properties, such as less oxygen and/or less acidity, is produced directly. This makes the further upgrading into liquid transportation fuels more cost effective due to less hydrogen being required. Energy is also saved for pyrolysis vapor cooling and pyrolysis oil reheating.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the exemplary embodiments of the present invention and the advantages thereof, reference is now made to the following description in conjunction with the accompanying drawings, which are briefly described as follows.

FIG. 1 is a schematic of a process for in-situ upgrading of pyrolysis vapor using a multi-layered catalyst bed, with multiple layers of the different catalysts, according to an exemplary embodiment.

FIG. 2 is a schematic of a process for in-situ upgrading of pyrolysis vapor using cascaded catalyst reactors (or beds), according to an exemplary embodiment.

FIG. 3 is a schematic of a process for in-situ upgrading of pyrolysis vapor using an acid catalyst in the presence of alcohol, according to an exemplary embodiment.

FIG. 4 is a schematic of a process for in-situ upgrading of pyrolysis vapor using a water-gas shift reaction catalyst and a hydrotreating catalyst, with multiple layers of the different catalysts, according to an exemplary embodiment.

FIG. 5 is a schematic of a process for in-situ upgrading of pyrolysis vapor using a water-gas shift reaction catalyst and a hydrotreating catalyst, using cascaded catalyst reactors (or beds), according to an exemplary embodiment.

FIG. 6 is a schematic of a process for in-situ upgrading of pyrolysis vapor using a cracking catalyst, a water-gas shift reaction catalyst, and a hydrotreating catalyst, with multiple layers of the different catalysts, according to an exemplary embodiment.

FIG. 7 is a schematic of a process for in-situ upgrading of pyrolysis vapor using a cracking catalyst, a water-gas shift reaction catalyst, and a hydrotreating catalyst, using cascaded catalyst reactors (or beds), according to an exemplary embodiment.

DETAILED DESCRIPTION

Illustrative embodiments of the invention are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. One of ordinary skill in the art will appreciate that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.

The present invention may be better understood by reading the following description of non-limitative embodiments with reference to the attached drawings wherein like parts of each of the figures are identified by the same reference characters. The words and phrases used herein should be understood and interpreted to have a meaning consistent with the understanding of those words and phrases by those skilled in the relevant art. No special definition of a term or phrase, for example, a definition that is different from the ordinary and customary meaning as understood by those skilled in the art, is intended to be implied by consistent usage of the term or phrase herein. To the extent that a term or phrase is intended to have a special meaning, for example, a meaning other than that understood by skilled artisans, such a special definition will be expressly set forth in the specification in a definitional manner that directly and unequivocally provides the special definition for the term or phrase. Moreover, various streams or conditions may be referred to with terms such as “hot,” “cold,” “cooled, “warm,” etc., or other like terminology. Those skilled in the art will recognize that such terms reflect conditions relative to another process stream, not an absolute measurement of any particular temperature.

The present application is directed to an improved biomass pyrolysis process that performs in-situ upgrading of pyrolysis-vapor using different catalysts. Specifically, a catalyst bed with multi-layered catalysts or cascaded catalytic reactors with different catalysts are implemented in a regular fast pyrolysis unit. The biooil produced this way will have improved properties, for instance, lower oxygen content and/or less acidity, over biooils produced from regular fast pyrolysis. The present application is also directed to systems for implementing such processes.

Referring to FIG. 1, a process 100 for in-situ upgrading of pyrolysis vapor using a multi-layered catalyst bed reactor 102 is illustrated. A biomass stream 104 and a recycled off-gas stream 106 are fed into a fluid bed pyrolysis reactor 108. In certain exemplary embodiments, the recycled off-gas stream 106 includes nitrogen (N₂). The recycled off gas stream 106 fluidizes the bed in the pyrolysis reactor 108. In certain exemplary embodiments, the biomass stream 104 includes wood sawdust, bark, yard waste, waste lumber, agricultural wastes, peat, paper mill wastes, cellulosic wastes, municipal solid waste, food processing wastes, sewage sludge, and the like. In certain embodiments, the biomass stream 104 can be dried prior to entering the fluid bed pyrolysis reactor 108. In certain exemplary embodiments, the biomass stream 104 is dried to less than 10 wt % moisture content. In certain exemplary embodiments, the biomass stream 104 is ground to form small particles, for instance, less than 3 millimeters (mm) in its shortest dimension.

The pyrolysis reactor 108 is any reactor type capable of completing a pyrolysis reaction involving thermal decomposition of the biomass stream 104 at short reaction times. The pyrolysis reaction is sometimes called “fast”, “flash”, or “rapid” pyrolysis. The reaction is conducted in a reactor type capable of high heat transfer rates to small biomass particles, in order to achieve the rapid increase in temperature of the particle that is necessary. Suitable examples of pyrolysis reactors include, but are not limited to, fluidized bed reactors, circulating fluidized bed reactors, and transport reactors. In fluidized bed reactors and circulating fluidized bed reactors, hot gases and solids are brought into intimate contact with the biomass particles in the biomass stream 104. In certain exemplary embodiments, the solids are normally inert, for instance, silica or sand. In transport reactors, either hot gas alone or a mixture of hot gas and solids may be used. All reactors generally require a significant recycled off-gas flow, usually from about 1 to about 10 times the weight of biomass stream 104 being processed. If the pyrolysis reaction is carried out in the absence of oxygen, for example, in a nitrogen atmosphere, then the non-condensable gases formed have significant contents of carbon monoxide, hydrogen, methane and other light hydrocarbons or organics, which can be burned. The pyrolysis reactor 108 is generally operated at conditions which promote maximum yield of organic liquid. In certain exemplary embodiments, the pyrolysis reactor 108 is operated at a temperature in the range of from about 400 degrees Celsius (° C.) to about 650° C., a vapor residence time of less than about 2 seconds, and at substantially atmospheric pressure. Generally, the pyrolysis reaction yields a pyrolysis vapor stream 110 that exits a top 108 a of the pyrolysis reactor 108.

Once the pyrolysis on the biomass stream 104 is complete, the pyrolysis vapor stream 110 is often passed through separation devices, such as filters or cyclones, in order to remove any entrained solid particles, or char, 112 a, 112 b, resulting from the pyrolysis reaction. In certain exemplary embodiments, the pyrolysis vapor stream 110 enters a first cyclone reactor 114 to separate pyrolysis vapors from entrained char. A pyrolysis vapor stream 116 exits the first cyclone reactor 114 and enters a second cyclone reactor 118 to further separate pyrolysis vapors from entrained char. A pyrolysis vapor stream 120 exits the second cyclone reactor 118 and is introduced at a top 102 a of the multi-layered catalyst bed reactor 102. In certain exemplary embodiments, the pyrolysis vapor stream 120 is substantially free of particles so as not to plug the catalyst bed reactor 102.

The catalyst bed reactor 102 includes multiple layers of the different catalysts. The pyrolysis vapor stream 120 passes through each catalyst bed, in sequence from the top 102 a to a bottom 102 b, in the multi-layer catalyst bed reactor 102. The selection and proper combination of different catalysts is important, as it determines the performance of the catalytic treatment of the pyrolysis vapor stream 120.

In certain exemplary embodiments, a top catalyst 102 c would be a zeolite type cracking catalyst, preferably HZSM-5, as this catalyst can be operated at a temperature between about 370 and about 410° C., at atmospheric pressure. The cracking catalyst will crack the hydrocarbon in the pyrolysis vapor stream 120. Suitable examples of other zeolite cracking catalysts for use include, but are not limited to, REX, REY, and USY zeolites. Any suitable temperature and pressure can be used, based upon the degree of cracking desired. Some zeolite type catalysts, such HZSM-5, are prone to coke or char formation on the catalyst. The extent of the coking can be controlled by the relative space velocity of the pyrolysis vapor stream in the catalyst bed. Other cracking catalysts, for example those used in catalytic crackers (for instance fluid catalytic cracking units), may be less prone to coking relative to zeolites. Other types of catalysts, such as alumina based catalysts, can be used as cracking catalysts and will have lower coking tendencies.

In certain exemplary embodiments, a middle catalyst 102 d would be a high temperature water-gas-shift catalyst, for example, a precious metal catalyst such as platinum (Pt)/mixed oxide, which are good for operating in the temperature range of from about 350 to about 450° C. The purpose of using a shift catalyst is to convert the water and carbon monoxide (CO) in the pyrolysis vapor stream 120 into hydrogen (H₂) and carbon dioxide (CO₂), thus providing the hydrogen required by hydrodeoxygenation or hydrotreating. The water-gas shift reaction catalysts generally include a transition metal or transition metal oxide. In certain exemplary embodiments, precious metal catalysts, such as platinum in a mixed oxide, are utilized for operating in a temperature range of from about 350 to about 450° C. The hydrogen is then available for the hydrotreating or hydrodeoxygenation. The relative space velocity of the hot vapor stream through the bed can be designed and controlled to produce the maximum amount of hydrogen. The limiting factor will be the amount of carbon monoxide present in the pyrolysis vapor stream. Since water-gas shift is an equilibrium process, injection of additional hot water vapor before this catalyst would drive the conversion of all of the carbon monoxide into carbon dioxide and produce more hydrogen.

A third catalyst 102 e would include a hydrotreating (or hydrodeoxygenation) catalyst. Suitable examples of hydrotreating or hydrodeoxygenation catalysts include, but are not limited to, any known nickel molybdenum (NiMo), cobalt molybdenum (CoMo), or noble metal catalyst supported on γ-alumina. Generally, such catalysts are commercially available. In certain exemplary embodiments, the reaction is generally run at a temperature in the range from about 350 to about 450° C., at atmospheric pressure. The hydrotreating removes the oxygen containing-hydrocarbons in the pyrolysis vapor.

In certain exemplary embodiments, a solid acid catalyst 102 f, such as sulfated zirconia, zeolite β, or Nafion-silicone disoxide (SiO₂) composite (SAC-13), can be added to the very bottom 102 b of the catalyst bed reactor 102 with an injection of an alcohol stream 124 to perform an esterification process. The alcohol stream 124 can include methanol or ethanol, and can be injected into the catalyst 102 f bed, catalyst bed reactor 102, or pyrolysis vapor stream 120 to support the esterification reaction. The purpose of using the catalyst 102 f is to reduce the acidity of pyrolysis vapor stream 120 by letting the carboxylic acid (e.g., acetic acid) in the pyrolysis vapor stream 120 react with the alcohol stream 124 to form ester and water. An upgraded pyrolysis vapor stream 130 is removed from the bottom 102 b of the catalyst bed reactor 102 and directed to a quench tower 134. The pyrolysis vapor stream 130 is generally less acidic and safer for transport through pipes and equipment.

The order in which the pyrolysis vapor stream 120 contacts the foregoing catalysts can be any order. In certain exemplary embodiments, the water-gas shift catalyst is generally contacted prior to the hydrotreating catalyst so that the water-gas shift reaction can produce hydrogen, which can be used in the hydrotreating reaction, and thereby make the process more efficient. In one embodiment, the cracking catalyst is contacted first, followed by the water-gas shift catalyst, hydrotreating catalyst, and then the acid catalyst. In another embodiment, the water-gas shift catalyst is contacted first, followed by the hydrotreating catalyst, the acid catalyst, and then the cracking catalyst.

The pyrolysis vapor stream 130 is quenched and converted into a liquid biooil product 140, and collected at a base 136 of the quench tower 134. A portion 140 a of the biooil product 140 is collected in a biooil collection tank 144, while a portion 140 b can be pumped via pump 146 through a heat exchanger 148 to produce a cooled biooil stream 150. In certain exemplary embodiments, the cooled biooil stream 150 is reintroduced at a top 134 a of the quench tower 134 to quench the pyrolysis vapor stream 130.

In certain exemplary embodiments, a biooil vapor stream 154 from the quench tower 134 is directed to a condenser 156 to cool and condense the biooil vapor stream 154 to produce a condensed biooil stream 158 and a non-condensable gas stream 160. In certain exemplary embodiments, the condensed biooil stream 158 is routed to the biooil collection tank 144. The biooil collected in tank 144 generally has an oxygen content in the range of from about 30 to about 40 percent (%) (dry, ash free basis) and a water content in the range of from about 15 to about 25%, depending on the operating temperatures of the quench tower and the condensers. The biooil product is generally phase stable and which may separate from a lighter density, more water rich product phase. Typical pH values for the biooil product are in the range of from about 2 to about 5.

FIG. 2 illustrates a process 200 for in-situ upgrading of pyrolysis vapor, according to another exemplary embodiment. The process 200 for in-situ upgrading of pyrolysis vapor is the same as that described above with regard to the process 100 for in-situ upgrading of pyrolysis vapor, except as specifically stated below. For the sake of brevity, the similarities will not be repeated hereinbelow. The process 200 utilizes cascaded catalytic reactors, each having a single type of catalyst therein.

Referring now to FIG. 2, the pyrolysis vapor stream 120 free of particles exits the second cyclone reactor 118 and is passed through a heat exchanger 202 to control the temperature of the pyrolysis vapor stream 120 to produce a pyrolysis vapor stream 204. The temperature of the pyrolysis vapor stream 120 is adjusted to achieve optimal conditions for catalysis. The pyrolysis vapor stream 204 is introduced into a first catalytic reactor 208. In certain exemplary embodiments, the first catalytic reactor 208 includes a zeolite cracking catalyst therein. A pyrolysis vapor stream 210 exits the first catalytic reactor 208 and is passed through a heat exchanger 212 to control the temperature of the pyrolysis vapor stream 210 to produce a pyrolysis vapor stream 214. The temperature of the pyrolysis vapor stream 210 is adjusted to achieve optimal conditions for catalysis.

The pyrolysis vapor stream 214 is introduced into a second catalytic reactor 218. In certain exemplary embodiments, the second catalytic reactor 218 includes a water-gas shift catalyst therein. A pyrolysis vapor stream 220 exits the second catalytic reactor 218 and is passed through a heat exchanger 222 to control the temperature of the pyrolysis vapor stream 220 to produce a pyrolysis vapor stream 224. The temperature of the pyrolysis vapor stream 220 is adjusted to achieve optimal conditions for catalysis.

The pyrolysis vapor stream 224 is introduced into a third catalytic reactor 228. In certain exemplary embodiments, the third catalytic reactor 228 includes a hydrotreating catalyst therein. A pyrolysis vapor stream 230 exits the third catalytic reactor 228 and is passed through a heat exchanger 232 to control the temperature of the pyrolysis vapor stream 230 to produce a pyrolysis vapor stream 234. The temperature of the pyrolysis vapor stream 230 is adjusted to achieve optimal conditions for catalysis.

The pyrolysis vapor stream 234 is introduced into a fourth catalytic reactor 238. In certain exemplary embodiments, the fourth catalytic reactor 238 includes an acid catalyst therein. The alcohol stream 124 can be injected with the pyrolysis vapor stream 234 to perform the esterification process and lower the acidity of the resulting upgraded pyrolysis vapor stream 240. The pyrolysis vapor stream 240 exits the fourth catalytic reactor 238 and is directed to the quench tower 134.

Generally, the processes of the present invention involves thermal conversion of biomass by pyrolysis, i.e., in a pyrolysis reactor. A greatly improved liquid, biooil product is obtained by the present process as the pyrolysis vapor is upgraded. The pyrolysis vapor is contacted with a cracking catalyst, a water-gas shift reaction catalyst, a hydrotreating catalyst and an acid catalyst. This particular selection of catalysts provides an upgraded vapor that is converted into a liquid product by a means such as by quenching, thus resulting in a biooil liquid so refined that it can be combined with crude oil to give a useful gasoline product. No additional refining is necessary. Further refining, of course, can be conducted to fine tune the properties of the biooil product, depending on the ultimate product desired.

The selection and proper combination of the different catalysts allows for upgrading of the pyrolysis vapor, and thereby provides the resulting refined biooil. The use of a cracking catalyst, in combination with a hydrotreating catalyst and a water-gas shift reaction catalyst, and an acid catalyst, can provide one with a liquid biooil product having reduced oxygen and water content as well as lowered acidity. In general, the pyrolysis vapor can contact the different catalysts in any order desired. The catalysts can be arranged in a multi-layer fashion, in separate reactors, or in a combination of such.

Contacting the catalysts with the pyrolysis vapor stream 120 can be conducted in any suitable fashion. In certain embodiments, the contacting is conducted in a single reactor where the catalysts are situated in a multilayer fashion. The vapor contacts each catalyst in order as situated in the multilayer fashion. In other embodiments, the catalysts are arranged in separate reactors, with the pyrolysis vapor being passed in sequence through each reactor. Heat exchangers can be included in between the cascaded reactors to heat or cool the pyrolysis vapor for the appropriate temperatures required by various upgrading catalysts. In addition, it would allow for easier sampling of the upgraded vapor for analysis after each stage, thus allowing more control over the process. In such an embodiment, the temperature and pressure for each reaction can be better fine tuned to control the reaction. Also, guard beds can be placed before each reactor to filter out unwanted materials, if so desired.

FIG. 3 illustrates a process 300 for in-situ upgrading of pyrolysis vapor using the acid catalyst, according to an exemplary embodiment. The process 300 for in-situ upgrading of pyrolysis vapor is the same as that described above with regard to the process 100 for in-situ upgrading of pyrolysis vapor, except as specifically stated below. For the sake of brevity, the similarities will not be repeated hereinbelow. Referring now to FIG. 3, the pyrolysis vapor stream 120 enters a catalyst bed reactor 302. The catalyst bed reactor 302 includes a solid acid catalyst bed 302 f with an injection of alcohol stream 124 to perform an esterification process. An upgraded pyrolysis vapor stream 330 is removed from a bottom 302 b of the catalyst bed reactor 302 and directed to the quench tower 134. The pyrolysis vapor stream 330 is generally less acidic and safer for transport through pipes and equipment.

FIG. 4 illustrates a process 400 for in-situ upgrading of pyrolysis vapor using a water-gas shift catalyst and a hydrotreating (or hydrodeoxygenation) catalyst, according to an exemplary embodiment. The process 400 for in-situ upgrading of pyrolysis vapor is the same as that described above with regard to the process 100 for in-situ upgrading of pyrolysis vapor, except as specifically stated below. For the sake of brevity, the similarities will not be repeated hereinbelow. Referring now to FIG. 4, the pyrolysis vapor stream 120 enters a catalyst bed reactor 402 having a top catalyst 402 d and a bottom catalyst 402 e. The catalyst bed reactor 402 includes multiple layers of the different catalysts. In certain exemplary embodiments, the top catalyst 402 d is a water-gas shift catalyst. In certain exemplary embodiments, the bottom catalyst 402 e is a hydrotreating catalyst. The pyrolysis vapor stream 120 passes through each catalyst bed, in sequence from a top 402 a to a bottom 402 b, in the multi-layer catalyst bed reactor 402. In certain exemplary embodiments, the water-gas shift catalyst is contacted first, followed by the hydrotreating catalyst. An upgraded pyrolysis vapor stream 430 is removed from the bottom 402 b of the catalyst bed reactor 402 and directed to the quench tower 134.

FIG. 5 illustrates a process 500 for in-situ upgrading of pyrolysis vapor, according to another exemplary embodiment. The process 500 for in-situ upgrading of pyrolysis vapor is the same as that described above with regard to the process 400 for in-situ upgrading of pyrolysis vapor, except as specifically stated below. For the sake of brevity, the similarities will not be repeated hereinbelow. The process 500 utilizes cascaded catalytic reactors, each having a single type of catalyst therein.

Referring now to FIG. 5, the pyrolysis vapor stream 120 is passed through a heat exchanger 512 to control the temperature of the pyrolysis vapor stream 120 to produce a pyrolysis vapor stream 514. The temperature of the pyrolysis vapor stream 120 is adjusted to achieve optimal conditions for catalysis. The pyrolysis vapor stream 514 is introduced into a first catalytic reactor 518. In certain exemplary embodiments, the first catalytic reactor 518 includes a water-gas shift catalyst therein. A pyrolysis vapor stream 520 exits the first catalytic reactor 518 and is passed through a heat exchanger 522 to control the temperature of the pyrolysis vapor stream 520 to produce a pyrolysis vapor stream 524. The temperature of the pyrolysis vapor stream 520 is adjusted to achieve optimal conditions for catalysis.

The pyrolysis vapor stream 524 is introduced into a second catalytic reactor 528. In certain exemplary embodiments, the second catalytic reactor 528 includes a hydrotreating catalyst therein. A pyrolysis vapor stream 530 exits the second catalytic reactor 528 and is directed to the quench tower 134. By upgrading the pyrolysis vapor in accordance with the processes 400, 500, the overall upgrading process is more thermally efficient. The heat loss due to condensation of pyrolysis vapor and the reheating of biooil is avoided. Furthermore, no hydrogen is needed, as hydrogen can be provided internally by the water-gas-shift reaction. In addition, the biooil produced from the quench tower 134 would have a lower oxygen content, lower water content, and lower acidity.

FIG. 6 illustrates a process 600 for in-situ upgrading of pyrolysis vapor using a cracking catalyst, a water-gas shift catalyst, and a hydrotreating (or hydrodeoxygenation) catalyst, according to an exemplary embodiment. The process 600 for in-situ upgrading of pyrolysis vapor is the same as that described above with regard to the process 100 for in-situ upgrading of pyrolysis vapor, except as specifically stated below. For the sake of brevity, the similarities will not be repeated hereinbelow. Referring now to FIG. 6, the pyrolysis vapor stream 120 enters a catalyst bed reactor 602 having a top catalyst 602 c, a middle catalyst 602 d, and a bottom catalyst 602 e. The catalyst bed reactor 602 includes multiple layers of the different catalysts. In certain exemplary embodiments, the top catalyst 602 c is a cracking catalyst. In certain exemplary embodiments, the middle catalyst 602 d is a water-gas shift catalyst. In certain exemplary embodiments, the bottom catalyst 602 e is a hydrotreating catalyst. The pyrolysis vapor stream 120 passes through each catalyst bed, in sequence from a top 602 a to a bottom 602 b, in the multi-layer catalyst bed reactor 602. The order in which the pyrolysis vapor stream 120 contacts the foregoing catalysts can be any order. In certain exemplary embodiments, the water-gas shift catalyst is generally contacted prior to the hydrotreating catalyst so that the water-gas shift reaction can produce hydrogen, which can be used in the hydrotreating reaction, and thereby make the process more efficient. In one embodiment, the cracking catalyst is contacted first, followed by the water-gas shift catalyst, and then the hydrotreating catalyst. In another embodiment, the water-gas shift catalyst is contacted first, followed by the hydrotreating catalyst, and then the cracking catalyst. An upgraded pyrolysis vapor stream 630 is removed from the bottom 602 b of the catalyst bed reactor 602 and directed to the quench tower 134.

FIG. 7 illustrates a process 700 for in-situ upgrading of pyrolysis vapor, according to another exemplary embodiment. The process 700 for in-situ upgrading of pyrolysis vapor is the same as that described above with regard to the process 600 for in-situ upgrading of pyrolysis vapor, except as specifically stated below. For the sake of brevity, the similarities will not be repeated hereinbelow. The process 700 utilizes cascaded catalytic reactors, each having a single type of catalyst therein.

Referring now to FIG. 7, the pyrolysis vapor stream 120 is passed through a heat exchanger 702 to control the temperature of the pyrolysis vapor stream 120 to produce a pyrolysis vapor stream 704. The temperature of the pyrolysis vapor stream 120 is adjusted to achieve optimal conditions for catalysis. The pyrolysis vapor stream 704 is introduced into a first catalytic reactor 708. In certain exemplary embodiments, the first catalytic reactor 708 includes a zeolite cracking catalyst therein. A pyrolysis vapor stream 710 exits the first catalytic reactor 708 and is passed through a heat exchanger 712 to control the temperature of the pyrolysis vapor stream 710 to produce a pyrolysis vapor stream 714. The temperature of the pyrolysis vapor stream 710 is adjusted to achieve optimal conditions for catalysis.

The pyrolysis vapor stream 714 is introduced into a second catalytic reactor 718. In certain exemplary embodiments, the second catalytic reactor 718 includes a water-gas shift catalyst therein. A pyrolysis vapor stream 720 exits the second catalytic reactor 718 and is passed through a heat exchanger 722 to control the temperature of the pyrolysis vapor stream 720 to produce a pyrolysis vapor stream 724. The temperature of the pyrolysis vapor stream 720 is adjusted to achieve optimal conditions for catalysis.

The pyrolysis vapor stream 724 is introduced into a third catalytic reactor 728. In certain exemplary embodiments, the third catalytic reactor 728 includes a hydrotreating catalyst therein. A pyrolysis vapor stream 730 exits the third catalytic reactor 728 and is directed to the quench tower 134. By upgrading the pyrolysis vapor in accordance with the processes 600, 700, the overall upgrading process is more thermally efficient. The heat loss due to condensation of pyrolysis vapor and the reheating of biooil is avoided. Also, a liquid biooil product is obtained that is refined such that the product can be combined with crude oil to produce gasoline. Furthermore, no hydrogen is needed, as hydrogen can be provided internally by the water-gas-shift reaction. In addition, the biooil produced from the quench tower 134 would have a lower oxygen content, lower water content, and lower acidity.

By upgrading pyrolysis vapor in accordance with the processes of the present invention, the overall upgrading process is more thermally efficient than conventional processes. Heat loss due to condensation of pyrolysis vapor and reheating of biooil is avoided. Furthermore, no hydrogen (H₂) is needed, as hydrogen can be provided internally by the water-gas-shift reactions. In addition, the biooil produced from the quench tower has less oxygen, less water, and fewer acids than biooils produced using conventional processes, and therefore has an improved quality over conventional biooils. By treating the pyrolysis vapor in accordance with the present invention, a liquid biooil product can be obtained that is already so refined that it can be combined directly, or with minimal further refining, to crude oil to make a gasoline product.

To facilitate a better understanding of the present invention, the following examples of certain aspects of some embodiments are given. In no way should the following examples be read to limit, or define, the scope of the invention.

EXAMPLES Example 1

The typical operating conditions for a multi-layer fixed-bed reactor would be:

-   -   Catalysts used: Top layer—HZSM-5 (cracking catalyst);         -   2nd layer—Pt supported on mixed oxide (water-gas shift             catalyst);         -   3rd layer—NiMo and CoMo Supported on γ-alumina             (hydrotreating catalyst);         -   Bottom layer—Zeolite β (acid catalyst).     -   Pressure: Atmospheric     -   Temperature: 350-400° C.     -   Volume Ratio: Determined by space velocities required; also         considering cost, generally         -   Top layer: 2nd layer: 3rd layer: Bottom layer=5:2:3:10     -   Expected Bio-oil Quality:         -   Oxygen content: <10 wt %         -   Water content: <5 wt %         -   pH: 5-6

Example 2

The typical operating conditions for an acid catalyst fixed-bed reactor would be:

-   -   Catalysts used: Zeolite β (acid catalyst).     -   Pressure: Atmospheric     -   Temperature: 350-400° C.     -   Expected Bio-oil Quality:         -   pH: 5-6

Example 3

The typical operating conditions for a multi-layer fixed -bed reactor would be:

-   -   Catalysts used: Top layer—Pt supported on mixed oxide (water-gas         shift catalyst);         -   2nd layer-NiMo and CoMo Supported on γ-alumina             (hydrotreating catalyst);     -   Pressure: Atmospheric     -   Temperature: 350-400° C.     -   Expected Bio-oil Quality:         -   Oxygen content: <10 wt %         -   Water content: <5 wt %

Example 4

The typical operating conditions for a multi-layer fixed -bed reactor would be:

-   -   Catalysts used: Top layer—HZSM-5 (cracking catalyst);         -   2nd layer—Pt supported on mixed oxide (water-gas shift             catalyst);         -   3rd layer-NiMo and CoMo Supported on γ-alumina             (hydrotreating catalyst).     -   Pressure: Atmospheric     -   Temperature: 350-400° C.     -   Volume Ratio: Determined by space velocities required; also         considering cost, generally         -   Top layer: 2nd layer: 3rd layer=5:2:3     -   Expected Bio-oil Quality:         -   Oxygen content: <10 wt %         -   Water content: <5 wt %

Therefore, the present invention is well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular embodiments disclosed above are illustrative only, as the present invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. While numerous changes may be made by those skilled in the art, such changes are encompassed within the spirit of this invention as defined by the appended claims. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular illustrative embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the present invention. The terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee. 

What is claimed is:
 1. A process for the thermal conversion of biomass comprising the steps of: a) thermal conversion of a biomass feedstock in a pyrolysis reactor; b) recovering a pyrolysis vapor from the reactor; c) passing the pyrolysis vapor in contact with an acid catalyst in the presence of an alcohol to produce an upgraded pyrolysis vapor; and d) converting the upgraded pyrolysis vapor from step c) into a liquid product.
 2. The process of claim 1, wherein the acid catalyst comprises a sulfated zirconium catalyst, a zeolite β or Nafion-SiO2 catalyst.
 3. The process of claim 1, wherein the acid catalyst comprises a zeolite β.
 4. The process of claim 1, wherein the alcohol is methanol or ethanol.
 5. The process of claim 1, wherein the alcohol is injected into a stream containing the pyrolysis vapor passed in contact with the acid catalyst.
 6. The process of claim 1, wherein the liquid product has a pH in a range of from about 2 to about
 5. 